Why is the sign in the formula Δy=VoyT - (1/2)at² negative in this problem

1. The problem statement, all variables and given/known data
A placekicker must kick a football from a point 36.0 m (about 40 yards) from the goal, and half the crowd hopes the ball will clear the crossbar, which is 3.05 m high. When kicked, the ball leaves the ground with a speed of 20.0 m/s at an angle of 53.0º to the horizontal.
(a) By how much does the ball clear or fall short of clearing the crossbar?
(b) Does the ball approach the crossbar while still rising or while falling?

2. Relevant equations
1.)Vox= Vo*CosΘ
2.)Voy= Vo*SinΘ
3.)Δx=x=VoxT where T (caps) is equal to time and not period.(its caps to discern from the sub 'ox')
4.)Δy= VoyT - (1/2)gt²